The value of sand as aggregate for concrete for the construction
industry and as sediment for artificial beach replenishment at tourist destinations
on Oahu has increased following a legislative moratorium on the mining of beach
sand. Concern for future shortfalls of sand supply prompted prospecting for
offshore deposits. Sand channels extend offshore from major valleys and coastal
embayments on Oahu. Most of these accumulations join sinuous deposits of
sediment ponded on ancient terraces that parallel the coastline. Sand cores were
collected from these mapped deposits. Statistical analysis of particle size distributions
of 279 samples from these cores reveals local areas that are promising for
future exploitation. In some areas, variations of grain size can be related to water
depth and distance from shore, but in most areas, grain sizes are not simply
related to the geographic distribution of sampled sand. Along the leeward Oahu
coast, size distributions are related to depth in core : 5 ft of fine sand covers
medium and coarse sand. Comparisons between samples from different locales
reveals relationships primarily to submarine geomorphology and secondarily to
coastal wave climate
